It is known in the welding art to employ a safety helmet having a face portion. Further, it is known in the art to provide an observation aperture in the face portion in order to allow the wearer to observe his work during a welding procedure. The helmet protects the wearer from sparks and flying debris which may be encountered during such a procedure.
In addition to functioning as a "window" for the wearer to observe his work, safety glass is also employed in welder's safety helmets in order to protect the wearer from the often intense and potentially hazardous light or electromagnetic radiation emissions associated with welding. Such emissions vary in wavelength from ultra violet, to the visible spectrum, to infra red, depending upon the nature of the welding equipment employed. Safety glass is used to block all but a minute amount of these intense emissions, thus allowing the welder to focus directly upon the welding task, without fear of eye damage.
Because of the nature of the glass employed, nearly one hundred percent of visible spectrum light is blocked. Thus, a person wearing a welder's safety helmet, and looking through the safety glass, would be essentially blinded to all but very intense light emissions. The welder's work site is often a potentially hazardous location on its own. At such a site, a "blinded" workman increases the potential for a hazard. Therefore, it is a common practice for welder's to orient themselves at their work site, including positioning their hands and equipment for welding, before moving the safety glass in front of their eyes.
It is also known in the art to provide a safety helmet with a light radiation blocking lens hingedly connected to the safety helmet, and a clear glass lens affixed in front of the observation aperture. Thus, the welder positions himself at the work site, observing his surroundings through the clear glass lens. Immediately prior to beginning to weld, the light radiation blocking lens is pivoted at the hinge to a position in front of the clear glass lens, and welding can then begin.
An example of a welder's helmet employing a hinged safety lens is disclosed in U.S. Pat. No. 2,719,972. As is shown therein, it is known to employ two hinged safety glasses, each for a separate task. For instance, one lens may be of the type employed in welding operations, while the other may be of the type used for cutting operations. Because the light radiation emissions during each procedure is different, different lenses are required for different tasks.
It is known in the art, that during welding operations, light radiation must be prevented from entering the welder's field of view, except that which is permitted to pass through the safety lens. For this reason, welder's safety helmets such as that disclosed in U.S. Pat. No. 2,719,972, often employ a complex series of fastening and securing devices, such as external springs and clamps. As described above, light radiation emissions are a potential hazard, any such emissions which enter the welder's field of view could permanently damage the welder's eyesight.
Welder's safety helmets having one or more hinged safety glass lenses have proven to be beneficial in the welder's art. However, those helmets heretofore known by the inventor have all included external safety lens securing and fastening means. As stated above, U.S. Pat. No. 2,719,972 employs a series of hold-down springs, external to the helmet itself. Further, the safety glass lenses themselves, and the frame structures supporting them, are also positioned externally on the helmet. This positioning exposes the lenses, the lens frames and the securing and fastening means to the potential of being knocked, butted and jarred by surrounding objects. As alluded to above, sites where welding takes place, such as construction sites and the like, are often hazardous places. This is so because there are often exposed support beams, various pieces of equipment and the like. This increases the likelihood that the external securing structures of a welder's helmet will be struck and damaged. Further, in such environments sparks and particles of molten metal are prevalent, posing a threat to exposed springs and clamps in the prior art structures.
A damaged safety lens will potentially be susceptible to light impedance failure. That is, if the frame supporting the safety lens is damaged, light radiation emissions from the welding procedure can enter the welder's field of view, causing sever eye damage.
Therefore, a need exists for a welder's helmet having an interchangeable safety lens structure which will securely position a safety lens over the wearer's field of view; which will effectively prevent light radiation emissions from entering the field of view other than through the safety glass; which will serve to prevent damage to the safety lenses and the structures which impede the entrance of the light radiation emissions; and, which will not require the use of external fastening or securing devices.